The past continuous tense is used to describe an ongoing action that was happening in the past. It is formed by using the past tense of the verb "to be" (was/were) followed by the present participle (-ing form) of the main verb.
For example:
- I was studying for my exam yesterday. - They were playing soccer in the park. - She was cooking dinner when the phone rang. - We were watching a movie at that time.
In these sentences, the past continuous tense is used to indicate that the actions were happening continuously in the past.